Identification of verotoxin type 2 variant B subunit genes in Escherichia coli by the polymerase chain reaction and restriction fragment length polymorphism analysis.

摘要: A set of synthetic oligonucleotide primers was designed for use in a polymerase chain reaction protocol to specifically detect the B subunit genes vtx2ha and vtx2hb, which code production VT2 (Shiga-like toxin II) variant cytotoxins VT2v-a VT2v-b, respectively. An additional amplified fragment common subunits genes. Subsequent restriction endonuclease digestion this amplicon permitted prediction specific genotypes on basis predetermined length polymorphisms. Genotypes 21 VT2-producing strains Escherichia coli were determined using reaction-restriction polymorphism procedure. Four contained target sequences only genes, 9 3 VT2v-b. For combination, one strain both two Two E. O91:H21 VT2v-b The reference coli, E32511, found contain targeted from whereas recombinant pEB1, possessed that gene. activities extracellular HeLa cells ranged 0.3 41.7 TCD50 per microgram protein carrying gene 0 50.0 (TCD50 is tissue culture dose by 50% affected), suggesting phenotypic expression does not correlate with genotype.